UPS software failing to run batch file on server 2012 when logged out

I have Riello UPS PowerShield (UPSMon) installed on Server 2012. In the event of a power failure UPSMon runs a script (Windows batch file) and then shuts down the server. However, the script only runs when I'm logged in to the server. When logged out, UPSMon still detects the power issue and initiates a server shutdown, but it fails to run the script.

Some more info:

UPSMon is running as a service using the local SYSTEM account.
SYSTEM account has full explicit permissions on the ProgramData/UPSMon folder (where the ups_shut.bat file is saved).
I didn't have this issue until moving from server 2003 to 2012, and I get the same issue on a different test machine using Windows 8.

Any ideas would be welcomed.